Abstract: The crankshaft is basically made up of a number of crank units, if we connect serval crank units in a certain phase, combine the front end, bank end and the banlance weight, then a crack shaft is formed. Based on this logic, this paper takes the crankshaft used in a non-road LR4 A engine as an example, describes its structural features an layout, and carries on the relevant analysis and summary.It finally forms a simple and convenient crankshaft modeling design method.